An art dealer who paid £8.3 million for a self portrait by Sir Anthony van Dyck yesterday said it was opportunity he "could not miss".

London-based Philip Mould, who is based in London, and his New York counterpart Alfred Bader secured the piece following an auction at Sotheby's in London, yesterday.

The hammer price for the picture, which measures 59.7cm by 47.3 cm, was £7.4 million. With buyer's premium added, the total cost was £8,329,250, Sotheby's said.

It had been expected to fetch between £2 million and £3 million.

Mr Mould said: "This is the most important 17th-century British portrait to come on the market in the last two decades. It was an opportunity we could not miss."

The sale broke the previous auction record for a work by Van Dyck (1599-1641) of £3 million - and also set a new auction record for a British 17th century portrait, Philip Mould Ltd said.

Van Dyck painted the self portrait in the last months of his life.

It had remained in the possession of the Earls of Jersey for almost 300 years and previously belonged to artist Sir Peter Lely. Mr Mould, who works as an art adviser to the Houses of Parliament, has also appeared on television shows including BBC's Antiques Roadshow.